The Prophet. Peace be upon him, said meaning wear white garments for they are purer and better. This is why white is worn well in Muslim lands.
the Arabs wear white thawbs. thawb is a garment close to what the prophet peace upon him wore. The non-Arab Muslims prefer white as well. The marketers and the advertisers know this very well and they dress their characters in white and they want to build authority. Doctors also your right to give an air of authority. Natural fibers are the best material to wear.
Islamic Principles Website 